Articulated caster

ABSTRACT

An apparatus for supporting an object includes a base assembly and at least three wheels pivotally attached to the base assembly. A pivot arm includes a flange plate at an upper end for attachment to the object. An opposite lower end of the pivot arm includes a universal joint for pivotal motion about two perpendicular axes that is attached to the base assembly. A brake assembly is attached to the pivot arm. The brake assembly includes a first disengaged position and a second engaged position that is latched. When the brake assembly is in the second position, a brake pad is forced downward below a level of a surface and into frictional engagement with the surface. More than one apparatus can also be attached to an adapter plate to provide greater floatation. Pivotal attachment to a support beam is also described.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention, in general relates to casters and, moreparticularly, to casters that are adapted for use on irregular surfaces.

Prior U.S. Pat. No. 5,507,069 that issued on Apr. 16, 1996, to the sameinventor describes a related type of articulated caster and itsdisclosure and contents are included herein by reference.

There is a need for casters to support and move objects over varyingtypes of terrain. Even concrete floors have small irregularities in thesurface that casters must pass over. These irregularities aresubstantial for the wheels of a caster to overcome when there is a heavyload on the caster.

The prior patent, mentioned hereinabove, discloses a unique mechanism bywhich a caster's trailing wheels can, at times, lag behind each otherand in so doing rise up over obstacles.

While this represents a substantial improvement in casters, there stillremain certain unsatisfied needs. For example, there is a need for asimple and effective braking mechanism for use with a caster.

Previous braking methods that apply friction to a wheel of a caster areineffective if there is a low coefficient of friction intermediate thewheel and the surface upon which the wheel is placed. This is becausesuch a strategy for braking relies upon friction between a wheel and thesurface to prevent movement of the object being supported.

Also, there is no way to vary the coefficient of friction at theinterface between the wheel and the surface. By definition, the wheelsof a caster must be durable. This generally translates into hard wheels,especially when heavy loads are carried. Hard wheels (steel, certaintypes of plastics, etc.) that can carry heavy loads tend to have arelatively low coefficient of friction. This is the opposite of what isdesired.

Often, the object being supported must be retained not only in place,but it must be prevented from moving at all with respect to the surface.Attempting to supply a brake force directly to a caster's wheel toprevent rotation of the wheel introduces play, even when the wheel is anon-pivoting fixed-direction type of caster.

When the caster is adapted to pivot (for steering purposes), there issubstantial movement that can occur even with a “locked” wheel allowingthe wheel to stay in position on the ground and pivot about a circle.This results in considerable movement of the payload.

Also, there is a long standing need to positively engage the brakingeffect of a caster when desired and to positively remove the brakingeffect when it is not desired. The braking mechanisms of certain priortypes of caster design do not totally engage or disengage. Consequently,a user may think a brake is fully applied when, in fact, it has onlybeen partially applied. Conversely, a user may think a brake is fullydisengaged when, in fact, it is only partially disengaged. This problemis also further aggravated by the fact that most users are unable todetermine which direction a braking lever adjacent to a wheel of acaster is urged for braking. Consequently, the user may think he hasremoved the braking from all four casters (on at each of four corners istypical for most objects) when, in fact, the braking mechanism remainsengages for one or more of the casters. This makes movement of theobject difficult to accomplish. Conversely, when the user thinks he hasapplied the braking force to all four casters and when some of them arenot engaged, the object (i.e., the load or cargo) may begin to move and“run away” from the user once it is released.

Also, all brakes wear. With certain prior types of casters, this meansthe braking force decreases with age as the braking mechanism wears.

Furthermore, stopping a wheel of the caster from rotating is a poorsolution at braking the load. The caster's wheels are typically hard andhave a low coefficient of friction intermediate the wheel and thesurface upon which the wheel is to be used. A high coefficient offriction wheel tends to be a soft wheel that wears quickly and is,therefore, either not used or available with casters that are intendedto support heavy loads.

Furthermore, when the wheel is used to brake a caster, there is no wayto vary the coefficient of friction intermediate the caster and thesurface upon which the caster is used.

Also floors, as mentioned hereinabove, are irregular. If an attempt ismade to apply a braking force from the caster directly to a surfaceunderneath the caster, it is desirable to accommodate fluctuations inthe distance the floor is disposed below the caster.

Also, it is desirable to be able to safely apply a caster brake while inmotion without risk of injury, for example, the caster running over thefoot of the user.

Prior art designs also shift the center of gravity of an applied loadwhen the caster changes direction.

Accordingly, there is a need for a braking caster that overcomes theseprior limitations.

Also, while the benefits of the caster that is disclosed in the priormentioned patent application are substantial, there are disadvantagesassociated with its design. For example, the ball and socket assemblythat it utilizes is difficult to manufacture and, therefore, expensive.It is time-consuming to assemble.

There is also a potential weakness at the point of connectionimmediately above the pivot ball that tends to limit the maximum amountof force (i.e., load) that can be accomplished.

Also, the ball and socket assembly requires structures that can supportboth the ball and the socket which tend to limit the range of casterapplications that can utilize such a design.

It is desirable to provide a stronger joint that has the additionalbenefits of being less expensive to manufacture and easier to assemblyas well as adapted for use, including retrofit, into a variety ofexisting caster applications.

It is also desirable to provide an articulated caster that can be usedin plurality to form a compound carriage system that is adapted tosupport a payload without a need to excessively elevate the payload.

Accordingly, there exists today a need for an articulated caster thatcan help ameliorate the aforementioned difficulties.

Clearly, such an apparatus would be a useful and desirable device.

2. Description of Prior Art

Casters are, in general, known. For example, the following patentsdescribe various types of these devices:

U.S. Pat. No. 5,507,069 to Willis, Apr. 16^(th) 1996;

U.S. Pat. No. 301,925 to Roux, Jul. 15^(th), 1884;

U.S. Pat. No. 344,988 to Richmond, Jul. 6^(th), 1886;

U.S. Pat. No. 1,622,447 to Kalberer, Mar. 29^(th), 1927;

U.S. Pat. No. 1,666,139 to Johnson, Apr. 17^(th), 1928;

U.S. Pat. No. 2,123,707 to Bloch, Jul. 12^(th), 1938;

U.S. Pat. No. 3,433,500 to Christensen, Mar. 18^(th), 1969;

U.S. Pat. No. 4,053,129 to Graff, Oct. 11^(th), 1977; and

U.K. Patent No. 4822 to Kendrick's, Dec. 18^(th), 1877.

While the structural arrangements of the above described devices, atfirst appearance, have similarities with the present invention, theydiffer in material respects. These differences, which will be describedin more detail hereinafter, are essential for the effective use of theinvention and which admit of the advantages that are not available withthe prior devices.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide an articulatedcaster that includes a braking mechanism.

It is also an important object of the invention to provide anarticulated caster that includes a braking mechanism that does not applyfriction to a wheel of the caster.

Another object of the invention is to provide an articulated caster thatincludes a braking mechanism that supplies a braking force directly fromthe caster to a surface upon which the caster is used.

Still another object of the invention is to provide an articulatedcaster that includes a braking mechanism that supplies a braking forcedirectly from the caster to a surface upon which the caster is used andwhich provides a coefficient of friction that is adapted for thesurface.

Still yet another object of the invention is to provide an articulatedcaster that includes a braking mechanism that supplies a braking forcedirectly from the caster to a surface upon which the caster is used andwhich provides a pad having a desired coefficient of friction that isadapted for the surface.

Yet another important object of the invention is to provide anarticulated caster that includes a braking mechanism that supplies abraking force directly from the caster to a surface upon which thecaster is used and which provides selection of a pad having a desiredcoefficient of friction that is adapted for the surface.

Still yet another important object of the invention is to provide anarticulated caster that includes a braking mechanism which preventsmovement of a load being supported by the caster with respect to asurface upon which the caster is used.

A first continuing object of the invention is to provide an articulatedcaster that includes a braking mechanism which supplies a braking forcedirectly from the caster to a surface upon which the caster is used thatis adapted for use with a plurality of casters that are used to supporta load that is being supported by the casters.

A second continuing object of the invention is to provide an articulatedcaster that includes a braking mechanism that can be locked in an offposition that does not increase friction of any wheel of the caster nordoes it increase friction between the caster and surface upon which thecaster is used.

A third continuing object of the invention is to provide an articulatedcaster that includes a braking mechanism that can be locked in an onposition.

A fourth continuing object of the invention is to provide an articulatedcaster that includes means for compensating for the wear of a padintermediate the caster and a surface upon which the caster is used.

A fifth continuing object of the invention is to provide an articulatedcaster that includes a braking mechanism which compensates forirregularities in the surface upon which the caster is used.

A sixth continuing object of the invention is to provide an articulatedcaster that provides for articulation about two simultaneous axes.

A seventh continuing object of the invention is to provide anarticulated caster that provides for articulation about two axes andwhich is inexpensive to manufacture.

An eighth continuing object of the invention is to provide anarticulated caster that includes a universal joint for articulationabout two simultaneous axes.

A ninth continuing object of the invention is to provide an articulatedcaster that provides for articulation about two axes and which isadapted to carry a heavy load.

A tenth continuing object of the invention is to provide an articulatedcaster that provides for articulation about two axes and which isadapted for use with a wide variety of objects.

An eleventh continuing object of the invention is to provide anarticulated caster that provides for increased load carrying capacitywithout an increase in the height above grade that the object beingsupported by the caster must be disposed.

A twelfth continuing object of the invention is to provide anarticulated caster that lessens a change in a center of gravity of anapplied load when the caster changes direction.

A thirteenth continuing object of the invention is to provide anarticulated caster that includes a brake actuation mechanism thatremains in a fixed position during movement of the caster.

A fourteenth continuing object of the invention is to provide anarticulated caster that includes a brake actuation mechanism thatdecreases the chance that injury might occur to a user, for example,having the caster run over a foot, when the user attempts to apply thebrake actuation mechanism during movement of the caster.

A fifteenth continuing object of the invention is to provide anarticulated caster that is adaptable to include a conventional type of auniversal joint.

A sixteenth continuing object of the invention is to provide anarticulated caster that includes three wheels that always define aplane.

A seventeenth continuing object of the invention is to provide aplurality of articulated casters that are connected together thatincludes three wheels that always define a plane.

Briefly, an articulated caster that is constructed in accordance withthe principles of the present invention has a base assembly comprised ofthree or more wheels that extend radially away from a center of the baseassembly. A pivot arm is attached at an upper end thereof to a flangeplate. The flange pate is attached (i.e., bolted) to an object to besupported by the caster. A lower end of the pivot arm is attached to thebase assembly by a pair of bolts that are part of a universal joint. Theuniversal joint allows for articulation of the pivot arm about two axessimultaneously. A brake mechanism is attached to the pivot arm and isadapted to urge a brake pad from a first retracted position in which thebrake pad is elevated above a plane of a floor and no braking force issupplied to a second extended position in which the brake pad isextended below the plane of the floor where the brake pad is infrictional cooperation with the floor and a substantial braking force isapplied. The use of a plurality of articulated casters that are attachedto an adapter plate is also described for use in supporting a heavierpayload as well as attachment to support beams.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in perspective of the top of an articulated caster.

FIG. 2 is a view in perspective of the bottom of the articulated casterof FIG. 1.

FIGS. 3 a–3 d include side views of a brake mechanism in an unlockedposition, locked, locking, and released positions.

FIG. 4 is a top view of the brake mechanism of FIGS. 3 a–3 d taken alongthe line 4—4 in FIG. 3 d.

FIG. 5 is a view in perspective of the bottom of a modified articulatedcaster.

FIG. 6 is a view in perspective of the top of the modified articulatedcaster of FIG. 5.

FIG. 7 is a view in perspective of the top of a second modifiedarticulated caster.

FIG. 8 is a view in perspective of the bottom of a third modifiedarticulated caster.

FIG. 9 is a view in perspective of a horizontal pivot arm attached to anarticulated caster.

FIG. 10 is a view in perspective of an interlocking system for gangingpairs of articulated casters together to make groups of four or more.

FIG. 11 is a view in perspective of the bottom of an alternativeinterlocking system for ganging pairs of articulated casters together.

DETAILED DESCRIPTION OF THE INVENTION

Referring on occasion to all of the drawing figures and in particularnow to FIG. 1 and FIG. 2 is shown, an articulated caster, identified ingeneral by the reference numeral 10.

A base assembly 12 preferably includes a lead wheel 14 and two trailingwheels 16, 18. All wheels 14–18 preferably rotate about a vertical axis20 that passes through a mounting bolt 22 of each wheel 14–20.

The two trailing wheels 16, 18 are preferably also staggered so thatthey are not parallel. This helps smooth movement when a surfaceirregularity is encountered.

A pivot arm 24 includes an upper end 24 a and an opposite lower end 24b. The upper end 24 a is attached to a flange plate 26. The flange plateincludes bolt holes 28 and is used to attach the caster 10 to an object(not shown) that is to be supported by the caster 10.

The pivot arm 24 passes through a correspondingly shaped opening 30 inthe base assembly 12. The base assembly 12 includes a pair of sidemembers 32 that extend down on opposite sides of the opening 30 to alocation that is, preferably, lower than that of an axle 34 of each ofthe wheels 14–18. The side members 32 are securely attached to the baseassembly 12.

All load (i.e., the weight of the object) that is applied to each caster10 is transferred through the pivot arm 24 to a lower end of both of theside members 32. This is described in greater detail hereinafter.

However, it is important to note that by transferring the load to alocation within the caster 10 that is proximate or below the axles 34,as the object is moved laterally (along the surface), there is no forceapplied to the caster 10 above the axles 34. This provides a loweffective center of gravity for the caster 10 as it supports the weightof the object, thereby making the caster 10 especially stable.

Referring now primarily to FIG. 2, the lower end 24 b of the pivot arm24 includes a first side 25 a and an opposite second side 25 b. Arectangular opening is provided in the lower end 24 b, of the pivot arm24 intermediate the first side 25 a and the second side 25 b. Therectangular opening is open at the lower end 24 b, and it extends upalong the longitudinal length of the pivot arm 24 for a predetermineddistance.

A first side plate 36 is attached to the first side 25 a, and a secondside plate 38 is attached to the second side 25 b. Attachment, as usedanywhere herein, is by any preferred method. It can include welding,molding together as a unit, bolts and nuts, or any other method.

A pivot block 40 is inserted in the space between the first and secondside plates 36, 38. The pivot block 40 can move in the space, as isdescribed hereinbelow, yet the fit between the pivot block 40 and theside plates 36, 38 includes minimal tolerance and, therefore, minimalslack. As perhaps best shown in FIG. 2, this arrangement provides forslidable interengagement between the pivot block 40 and side plates 36,38. More particularly, the opposite surfaces of the illustrated pivotblock 40 slidably engage respective ones of the side plates 36,38 sothat relative movement between the pivot arm 24 and pivot block 40 isrestricted to rotation about a single axis (defined by a bolt in thepreferred embodiment, as will be discussed).

A first bolt 42 passes through an opening in the first side 25 a,through a coincident opening in the first side plate 36, through acoincident opening through the pivot block 40, through a coincidentopening in the second side plate 38, and through a coincident opening inthe second side 25 b. The first bolt 42 is secured in place, preferablyby a lock nut 42 a or other locking means.

The pivot arm 24 is adapted to pivot from side to side, as shown byarrow 44, with respect to the pivot block 40. This defines a first axisof pivoting for the pivot arm 24 with respect to the base assembly 12(i.e., through a longitudinal axis of the first bolt 42). Obviously, thepivot arm 24 cannot pivot more than the space intermediate the pivot arm24 and the opening 30 in the base assembly 12 allows.

The pivot block 40 includes a pair of threaded extensions (not shown)that extend from the center of the pivot block 40 and which pass throughtwo openings provided on opposite sides of the side members 32 as low aspossible. A grease fitting 46 is preferably attached to each threadedextension wherein each threaded extension includes an opening that isadapted to convey grease into the pivot block 40. If preferred, only onegrease fitting 46 may be used. Such lubricant enhances slidingengagement between the pivot block 40 and the side members 32. It isparticularly noted that the ends of the pivot block 40 present surfaces,each of which each slidably engages a respective one of the opposedinside surfaces of the side members. Moreover, this slidinginterengagement between the pivot block 40 and side members 32 serves torestrict relative movement therebetween to rotation about a single axisdefined by the threaded extensions of the pivot block 40 in thepreferred embodiment.

A pair of lock nuts 48 cooperate with threads on the threaded extensionsand are used to secure the pivot block 40 to the side members 32. Thepivot block 40, therefore, acts as a second bolt to secure the pivot arm24 to the base assembly 12 and as one which includes a longitudinal axisthat is always perpendicular with respect to the first bolt 42.

Another embodiment, also preferable, is to include the grease fitting 46in a hollow bolt (in this alternate embodiment, also as shown, thehollow bolt is identified by reference number 48), which, accordingly,shows the head of the hollow bolt 48 and where the hollow bolt 48 screwsinto threads that are provided in an end of the pivot block 40.

The pivot block 40 is adapted to pivot from side to side, as shown byarrow 50, with respect to the side members 32, and within the limits asafforded by the opening 30. This defines a second axis of pivoting forthe pivot arm 24 (i.e., around the longitudinal center of the pivotblock 40) with respect to the base assembly 12.

Accordingly, the caster 10 is adapted to pivot about two axes that areperpendicular to each other with respect to the base assembly 12. It ispossible to use angles other than perpendicular for special purposes.The longitudinal axis of the first bolt 42 is in line with the normaldirection (i.e., line) of travel. The longitudinal axis of the pivotblock 40 (the second bolt) is preferably disposed at a 90 degree anglewith respect to the normal direction of anticipated movement by thecaster 10. This allows the wheels 14–18 of the caster to overcomesurface irregularities with ease.

Referring now in particular also to FIGS. 3 a–3 d and also on occasionto FIG. 4, is shown an optional brake assembly, identified in general bythe reference numeral 100.

FIG. 3 a shows the brake assembly 100 in a first retracted position inwhich a brake pad 102 is elevated above a surface 104.

A return spring 106 is holding the brake assembly 100 in the firstretracted position. This ensures that no braking force is applied whenthe brake assembly 100 is released (i.e., when it is in the firstposition).

A pivot rod 108 is pivotally attached at an upper end to a brake lever110 and at an opposite end to a brake pad support member 112. The brakepad support member 112 is attached over one end of the first bolt 42,about which it is adapted to pivot.

There are of course other ways of pivotally attaching the brake padsupport member 112. For example, a sleeve (not shown) may be welded tothe pivot arm 24 and another bolt may be used to engage threads in thesleeve allowing the brake pad support member 112 to pivot about theother bolt or sleeve as desired. Alternatively, a pivot pin may be usedas well as bushings, etc. These variations are useful in diminishingwear or improving smoothness of operation.

A first stop pin 114, attached to the pivot arm 24, prevents the brakepad support member 112 from retracting further, as urged by the returnspring 106.

The pivot rod 108 preferably bears against a compression spring 116. Inthe first position, the compression spring 116 is somewhat relaxedbecause the pivot rod 108 is not supplying a force that is attempting tocompress it.

A latch plate 118 is attached to one side of the pivot arm 24. The latchplate 118 includes an upper tapered surface and a flat bottom surface. Abrake release lever 120 includes a shaft 122 that includes a first end122 a which passes through a hole provided in one side of the brakelever 110. A shaft nut 123 secures the shaft to the brake lever 110. Theshaft 122 is adapted to rotate and tilt slightly within the holeprovided.

The shaft 122 includes an opposite end 122 b that passes through a slot124 provided in an opposite side of the brake lever 110. An end rod 126is attached to the opposite end 122 b of the shaft 122. The end rod 126retains the opposite end 122 b of the shaft 122 in the slot 124.

One end of the return spring 106 is attached to one end of the end rod126. The return spring 106 tends to urge the opposite end 122 b of theshaft 122 of the brake release lever 120 to the left of the slot 124, asshown (i.e., toward the pivot arm 24). The return spring 106 also urgesthe brake release lever 120 toward the first position. In the firstposition, the shaft 122 is disposed adjacent to the left side of theslot 124 and above the latch plate 118.

As is described in greater detail hereinafter, the opposite end 122 b ofthe shaft 122 is adapted to extend over the upper tapered surface of thelatch plate 118 as it is lowered. Once the shaft 122 is below the flatbottom surface of the latch plate 118, the return spring 106 urges theopposite end 122 b under the flat bottom surface, thereby retaining theshaft 122 and brake lever 110 in a second position in which a brakingforce is applied.

FIG. 3 b shows the brake assembly 100 as a braking force is beingapplied. The brake lever 110 has been urged downward sufficiently sothat a bottom edge of the brake pad 102 is beginning to contact thesurface 104. The brake pad 102 is a replaceable wear item that is chosenfor the specific application to provide an optimum coefficient offriction intermediate the brake pad 102 and the surface 104.

The opposite end 122 b is extended away from the pivot arm 24 by thelatch plate 118. Careful examination reveals that in FIG. 3 b, theopposite end 122 b of the shaft 122 is on the verge of being urgeddownward sufficient to clear the flat bottom surface of the latch plate118. The return spring 106 is fully extended.

FIG. 3 c shows the brake assembly 100 in the second fully engagedposition. The brake lever 110 has been lowered by the user sufficient sothat the shaft 122 has cleared the bottom of the latch plate 118. Thereturn spring has urged the opposite end 122 b of the shaft 122 to theleft of the slot 124 and under the flat bottom surface of the latchplate 118 where the latch plate 118 now retains the brake lever 110 inthe second position.

In this position, the brake pad 102 is lowered an amount sufficient tocause the lower surface of the brake pad 102 to be disposed below thesurface 104. This preferably compresses the spring 116 and brake pad102, or it may alternatively attempt to raise the object, or both. It isgenerally not preferred that the object be raised a greater amount abovethe surface 104 when the brake assembly 100 is engaged. A positivefrictional engagement intermediate the pivot arm 24 of the caster 10 andthe surface 104 by the brake pad 102 is what is desired and attained.

This eliminates the possibility of movement occurring intermediate thewheels 14–18 and the surface 104, a problem with prior types of casterbrakes which can cause unwanted movement of the object being supportedby the caster 10. It does not matter if the wheels 14–18 move or not,the object is stable and the caster 10 is applying a braking forcedirectly to the surface 104.

Depending on the intended application of the caster 10, the amount ofcompression of the pad 102, the material chosen for the pad 102, and thestroke of the brake lever 110 (i.e., the downward and upward range ofextension of the brake pad 102) are varied as desired. These and otherfactors are all design-specific variables. Accordingly, the brakeassembly 100 is locked and engaged with the surface 104. It is latchedin the second position and cannot be dislodged or released withoutfurther action, as described hereinafter.

It is also readily apparent to the user whether or not the brakeassembly 100 is engaged. If the brake lever 110 is raised (i.e., if itis close to the flange plate 26), the brake is in the first position andno braking force is applied. If the brake lever 110 is displaced awayfrom the flange plate 26, it is in the second position and maximumbraking force is applied. A second stop pin 128 prevents over rotationof the brake pad support member 112.

The spring 116 is maximally compressed in the second position. Thisallows a constant force to be applied to the brake pad 102. The spring116 also compensates for irregularities in the surface 104 and also forwear of the brake pad 102 over time.

FIG. 3 d shows the brake assembly 100 being released from the secondlatched position. As shown, it is ready to automatically retract, underforce supplied by the return spring 106, back into the first position.

To release the brake assembly 100, the brake release lever 120 is urgeddownward. As the brake release lever 120 is urged downward, the end rod126 rotates. As the end rod 126 rotates, a bottom portion thereofcontacts and bears against a brake release pin 130 that is attached tothe brake lever 110.

As additional force is applied to the brake release lever 120 in adownward direction, the end rod 126 continues to bear against the brakerelease pin an amount sufficient to urge the opposite end 122 b of theshaft 122 away from the pivot arm 24 until the opposite end 122 b clearsthe latch plate 118, as shown in FIG. 3 d.

The brake lever 110 is now free to return to the first position.Normally, the user allows the brake lever 110 to return quickly with asnap. An audible snap is heard on engagement and also on release. Thespring 116 also supplies a force that, on release, helps urge the brakelever 110 to return to the first position.

If for some reason (i.e., an especially sensitive load being supported)and the user preferred, he or she could also gently allow the brakelever 110 to return to the first position rather than releasing allcontact and allowing return spring 106 to urge it back abruptly.

Referring back to FIG. 4 momentarily, a roller sleeve 131 is disposedover the shaft 122 and is free to rotate about the shaft. The rollersleeve 131 is in contact with the latch plate 118 and because itrotates, it allows for easier and smoother operation.

Several important advantages are provided by the brake assembly 100.First, the location of brake is always the same when viewed from above.This allows the user to quickly access and apply the brake whereas withprior art caster brakes that are disposed on the wheels, their positionvaries and accordingly, they can not be quickly accessed as the wheelswobble or change directions.

Second, the brake can be applied safely and easily even while intransit. With prior art caster brakes, there is danger that the user canactually place his foot under the wheels where it can be run over orseverely pinched. While not generally preferred, in an emergency or inanticipation of a needed stop, the brake assembly 100 can be quickly,safely, and predictably applied while in motion.

Third, the brake assembly 100 has two positions. The first position isno brake force whatsoever is applied. The second position is full,normal brake force is applied. The brake is either set (applied) or itis not. This produces predictable results. Prior caster brakes produceuncertain variable results where the braking force can vary widely.Worse yet, this variance can occur without any tactile or visualfeedback occurring.

Prior caster brakes also are not securely latched and therefore areprone to sudden unpredictable release with possible damage to the objector even impact to people and other objects occurring.

Fourth, the report (noise) that occurs on setting (when the latch bar122 snaps into place) and release provides a clear indication of thebraking status to the user. When the brake is set, the user feels thisengagement, typically through his shoe and into his foot. It issimilarly felt on release. Either position can be verified visually aswell, thereby providing confirmation of position via three senses,hearing, feeling, and sight.

Referring now to FIG. 5 and FIG. 6, is shown a modified articulatedcaster, identified in general by the reference numeral 200.

While the articulated caster 10, can of course be scaled to any desiredsize to accommodate a need for greater (or lesser) payload (i.e.,carrying capacity), there is a potential disadvantage that can arisewhen substantially heavier payloads are encountered and a mere increasein the size of the articulated caster 10 is employed. That potentialdisadvantage is for the flange plate 26 to be elevated substantiallyhigher as a result of an increased wheel 16 diameter size.

The modified articulated caster 200 solves this potential disadvantageby arranging three (or any number) of the articulated casters 10together and attaching the flange plates 26 of each to an adapter plate202.

The adapter plate 202 includes gusset plates 204 that are added toreinforce it, as necessary. Each of the flange plates 26 is secured tothe adapter plate 202 by a plurality of bolts 206.

An enlarged pivot arm 208 is similar to the pivot arm 24 of thearticulated caster 10. An enlarged first bolt 210 is used to secure theenlarged pivot arm 208 to an enlarged pivot block 212.

The enlarged pivot arm 208 is adapted to pivot about a centerlongitudinal axis of the enlarged first bolt 210 with respect to theenlarged pivot block 212.

A pair of enlarged threaded extensions 214 that extend from oppositesides of the enlarged pivot block 212 each pass through one of a pair ofenlarged side members 216. A pair of enlarged lock nuts 218 secure eachend of the enlarged pivot block 212 to one of the enlarged side members216.

The enlarged pivot block 212 is adapted to pivot about a centerlongitudinal axis thereof with respect to the enlarged side members 216.

Together, the enlarged pivot block 212 and the enlarged first bolt 210provide two-axis pivoting (i.e., a universal joint) for the enlargedpivot arm 208 with respect to the adapter plate 202 within a spaceprovided by an enlarged opening 220 in the adapter plate 202.

An enlarged flange plate 222 is attached to an upper end of the enlargedpivot arm 208 and is used to attach the modified articulated caster 200to either a platform or directly to a heavy object (not shown) with asubstantial increase in carrying capacity and only a slight increase inheight above grade of the enlarged flange plate 222 as compared to thatof the flange plate 26.

Another benefit provided by the modified articulated caster 200 is anability for all castor wheels 14, 16, 18 to individually adapt to smallchanges in the grade without substantially affecting the plane of theadapter plate 202 or the heavy object. In other words, the heavy objectis not raised or lowered with respect to grade as the individual casterwheels 14–18 pass over small changes or fluctuations in the surface uponwhich they bear.

This makes is easier to move the heavy object because horizontalmovement is free of vertical movement. It also provides a smoother ridefor the heavy object, which does not rise and fall in response to thesmall fluctuations experienced by the wheels 14–18. This smoother ridehelps prevent damage to the heavy object, much the same as thearticulated caster 10 provides a smoother, safer ride for the objectthat it supports during transport.

Another benefit provided by the modified articulated caster 200 is thatsubstantial changes in grade, for example changes in the slope of thegrade that are encountered, are compensated for by movement (i.e., arising and falling) of the individual wheels 14–18 as well as by thevarious articulated casters 10.

As the articulated casters 10 respond to changes in grade or when theymust rise over more substantial objects (not shown), these changes aretransferred to the adapter plate 202, which pitches in response to thesevariations. However, the heavy object remains substantially unaffected,disposed on the same plane above grade, due to the universal jointaction provided by the mounting of the enlarged pivot arm 208 withrespect to the adapter plate 202.

The combined ability of the individual articulated casters 10 to adaptto changes in grade by the wheels 14–18, and of the adapter plate 202 toadapt to more substantial changes in grade provides a method ofsupporting an object (or heavy object) that allows for optimum ease oftransport, maintains the object at nearly a predetermined elevationabove grade, keeps that elevation as low as possible even when asubstantial carrying capacity is required, and isolates the payload(i.e., the object or heavy object) from fluctuations that occur on thesurface. Rolling resistance is actually decreases. It becomes easier tochange direction as well. Greater and more uniform floatation over thesurface is attained as well.

Of course, any number of the articulated casters 10 can be used with amodified adapter plate (not shown). It is also possible to duplicate theoverall process described above for even larger payloads or whenevergreater floatation, less rolling resistance, or easier direction changeis desired. For example, the enlarged flange plate 222 of the modifiedarticulated caster 200 can be attached to a modified enlarged adapterplate (not shown) in which a plurality of the modified articulatedcasters 200, each of which having a plurality of articulated casters 10,can be used.

It is noted that typically, as more and more casters 10 are used, theirsize is scaled down accordingly. This provides the desired benefits withlower structures that better distribute the load and compensate forsurface irregularities. Smaller wheels 14, 16, 18 can be used withmultiple groupings of the casters 10 and still climb over substantialobstacles because of the articulation and floatation characteristicsobtained.

A preferred method of distributing the load over a number of differentcarriages (i.e., the articulated casters 10) through the universal (orcross-axis) type of joints is herein disclosed. It is also possible tomount any of the joints (for the articulated caster 10 or the modifiedarticulated caster 200) in a manner that provides pivotal motion aboutonly one axis, instead of about two axes simultaneously, as thepreferred embodiments herein disclose.

The modified articulated caster 200 can, of course, also be used withthe brake assembly 100, as disclosed for with the articulate caster 10,as desired. If desired, a modified enlarged brake assembly (not shown)can be attached to the enlarged pivot arm 208.

Referring now to FIG. 7 is shown a second modified articulating caster,identified in general by the reference numeral 300.

The second modified articulated caster 300 includes a central beam 302to which a payload object (not shown) is attached to a center recess 304thereof.

A pair of transverse beams 306 are attached to opposite ends of thecentral beam 302 by an end bolt 308 (only one shown) that are located ateach end of the central beam 302.

Each of the transverse beams 306 is adapted to pivot around the axis ofthe end bolts 308 a limited amount.

Attached to each end of each transverse beam 306 is a second transversebeam 310. Each second transverse beam 310 is adapted to pivot around asecond end bolt 312 that secures the second transverse beam 310 to eachend of the transverse beam 306.

Accordingly, pivoting about two axes is provided, the first axis beingwith respect to a center longitudinal axis of the end bolt 308 and thesecond being with respect to a center longitudinal axis of the secondend bolt 312, the two axes being perpendicular with respect to eachother.

The end of each of the second transverse beams 310 is pivotally attachedto a caster assembly 314 by a caster pivot bolt 316. The caster pivotbolt 316 provides an axis that is parallel to that of the second endbolt 312 and it allows the caster assembly 314 to articulate about thecaster pivot bolt 316.

This allows the smaller caster assemblies 314 to articulate about thisaxis to accommodate smaller fluctuations in the surface while the secondend bolt 312 allows the second transverse beams 310 to pivot about aparallel axis to accommodate larger variations in the grade of thesurface without substantially affecting the position of the central beam302. Usually, the smaller caster assemblies 314 are able to adapt andaccommodate the greater part of any variations in the grade of thesurface.

A lower caster pivot bolt 318 includes a longitudinal axis that isparallel to that of the end bolts 308 and allows the caster assemblies314 to pivot about this axis to accommodate smaller grade fluctuationswhile the transverse beams 306 similarly pivot about the end bolts 308to accommodate larger grade fluctuations.

It is important to note that the second transverse beam 310 extends outof the side of the caster assembly 314. This provides substantialbenefits where low structure height is attained. This general concept isdiscussed in greater detail hereinafter (see discussion appertaining toFIG. 9).

Referring now to FIG. 8 is shown a third modified caster 400 thatincludes a conventional type of a universal joint 402 attached to amodified pivot arm 404 and to a pair of second modified side members406.

The second modified side members 406 are each adapted to retain abearing race into which the end of the universal joint 402 is secured.

The modified pivot arm 404 is adapted to retain a pair of bearing racesinto which the two remaining ends of the universal joint 402 aresecured.

Accordingly, the modified pivot arm 404 is adapted also to pivot abouttwo axes that are perpendicular with respect to each other, each one ofthe two axes passing through an opposite end of the universal joint 402.

While the universal joint 402 may be used to provide the desiredarticulation for the third modified caster 400, it may be more difficultto assemble, maintain, or replace that the previously disclosedembodiments and it is reserved for those applications where it use ispreferred.

Referring now to FIG. 9 is shown a horizontal pivot arm 500. Thehorizontal pivot arm 500 does not extend upward from the caster 10 butrather extends out from the side while still maintaining the full rangeof articulation as previously described. A very low profile is alsoachieved because the horizontal pivot arm 500 does not extend upward.Other substantial benefits are also attained by use of the horizontalpivot arm 500 and are described hereinafter.

Each end of the horizontal pivot arm 500 is attached to one of thecasters 10. Only the right caster 10 is shown in the drawing figure. Theleft caster is not shown to better illustrate how the horizontal pivotarm 500 is attached to each of the casters 10 so as to maintainarticulation about the two axes.

The horizontal pivot arm 500 is secured to a pair of raised side members506 by a pair of bolts 508. Each of the raised side members 506 are, inturn, pivotally attached to the pivot block 40 by the first bolt 42. Thethreaded extensions of the pivot block 40 are secured by the pair oflock nuts 48 and pivotally secure the pivot block 40 to a secondmodified side member 510 and to an opposite side member 512.

The second modified side member 510 is disposed between two of thecaster 10 wheels 14, 16. A preferred direction of movement by the caster10 is shown by arrow 514. The second modified side member 510 includes aplane that generally aligns with the arrow 514.

An enlarged side member opening 516 is provided in the second modifiedside member 510 through which the horizontal pivot arm 500 extends. Theenlarged side member opening 516 provides clearance for the horizontalpivot arm 500 to move relative to the second modified side member 510 asthe caster 10 changes attitude during transit in response toirregularities of the floor surface beneath the caster 10.

The opposite side member 512 does not require the enlarged side memberopening 516 because the horizontal pivot arm 500 does not pass throughit, although the enlarged side member opening 516 can be included in theopposite side member 512, if desired.

The horizontal pivot arm 500 includes a lower portion in the middleidentified in general by the reference numeral 518. The lower portion518 includes a flat bottom member 520 connected to two angled sides 522.

A circular bearing shaft 502 is attached to an outside of the lowerportion 518, below the flat bottom member 520.

A center load point 504 opening is provided proximate the bearing shaft502. The circular bearing shaft 502 is useful for connecting a pluralityof the horizontal pivot arms 500 together, for multiple ganging of thecasters 10, and it use is described in greater detail hereinafter.

The lower portion 518 keeps the geometry low, which allows for a loweredelevation of any object, which is preferred. The horizontal pivot arm500 allows for connection together of a pair of casters 10 (only the oneis shown) to divide and support the weight of the load between them.Accordingly, each caster 10 supports only about one-half the load whilestill fully adapted to articulate about the two axes with respect to thehorizontal pivot arm 500.

Referring now to FIG. 10 is shown an interlocking system, identified ingeneral by the reference numeral 550. Four casters 10 are each connectedtogether in pairs by one of the horizontal pivot arms 500.

The two pairs of interconnected casters 10 are then disposed in aparallel spaced-apart orientation. An intermediate member 600 is used toconnect the two pairs of casters 10 together and it includes a loweredcenter portion and a pair of opposite ends 602, 604.

The opposite ends 602, 604 include side cutouts 606 that allow each endof the intermediate member 600 to be placed atop a center of the lowerportion 518 of a respective one of the horizontal pivot arms 500. Anarcuate cutout 608 is provided at each of the opposite ends 602, 604.

The arcuate cutout 608 rests on top of the bearing shaft 502 therebyallowing for side to side articulation of the intermediate member 600along a center longitudinal axis of the bearing shaft 502 and withrespect to each of the horizontal pivot arms 500. A center load pointconnection 610 allows passage of a load member 612 to the horizontalpivot arm 500 or, if preferred, the connection can occur within theopposite ends 602, 604, as desired. The load member 612 conveys theweight of the load to the device.

The intermediate member 600 is simply placed atop the two horizontalpivot arms 500. The arcuate cutout 608 and the side cutouts 606 securethe two horizontal pivot arms 500 to the intermediate member 600. Inuse, any applied load only tends to further urge the intermediate member600 down thereby further securing it to the two horizontal pivot arms500. This allows for rapid “ganging” (i.e., joining) together of pairsof the casters 10.

A second bearing shaft 614 attached to the intermediate member 600allows another intermediate member (not shown) to be placed over two ofthe intermediate members 600 thereby connecting eight casters 10together. This further distributes the weight of the load while allowingeach individual caster 10 to articulate over surface irregularities.

This results in the capacity to transport up to heavy loads that are notelevated above the surface a significant amount and to do so withespecially low rolling resistance. Also, being able to utilize a greatmany wheels 14, 16, 18 to support a load (whenever two or more of thecasters 10 are used) allows for a wide selection in the type of materialused to form the wheels (the portion that contacts the surface). Softermaterials can be used as well as hard materials.

A wide range of design flexibility is thereby attainable. Materials, forexample, that can withstand insertion into an environmental chamber andwhich can experience a wide temperature variation, but which have alimited load carrying ability can now be used to form the wheels 14, 16,18 when multiple groups of the casters 10 are ganged together. Othermore economical materials can similarly be used. Materials that provideincreased friction, low rolling noise, etc. can instead be used to formthe wheels 14, 16, 18 that previously, when a single type of aconventional caster (not shown) was used, were not viable designchoices.

Referring now to FIG. 11 is shown another method for ganging multiplepairings of the casters 10 together. The method shown includes pivotbolts 700, 702 that pivotally secure the assemblies together, which passthrough openings that are provided. For certain applications, this ispreferred. The example shown includes eight casters 10, although anynumber of casters 10 can be connected together, as desired, in any of avariety of possible ways.

The invention has been shown, described, and illustrated in substantialdetail with reference to the presently preferred embodiment. It will beunderstood by those skilled in this art that other and further changesand modifications may be made without departing from the spirit andscope of the invention which is defined by the claims appended hereto.

For example, the caster 10 can include a newly designed type of abraking system or an older conventional type of caster brake thatapplies force directly to any of the wheels 14, 16, 18, if preferred. Itis also possible to provide braking by forcing two of the wheels intonon-parallel positions with respect to each other.

1. An articulated caster, comprising: (a) a base assembly including abase and at least three caster wheels attached to said base, with thebase assembly presenting a substantially flat base surface; (b) a pivotarm presenting a substantially flat arm surface; and (c) a pivot blockthat pivotally interconnects the base assembly and the pivot arm topermit relative pivotal movement therebetween about two axes, said pivotblock including first and second substantially flat surfaces, with thefirst surface slidably engaging the base surface of the base assembly torestrict movement about a first one of the axes and the second surfaceslidably engaging the arm surface of the pivot arm to restrict movementabout a second one of the axes.
 2. The articulate caster of claim 1wherein said pivot arm is adapted to extend upwardly from said baseassembly.
 3. The articulate caster of claim 1 wherein said pivot arm isadapted to extend laterally away from said base assembly.
 4. Thearticulate caster of claim 1 wherein said pivot arm is adapted to extendlaterally through an enlarged side opening provided in said baseassembly.
 5. The articulated caster of claim 1; an adapter member; asecond base assembly spaced from the first-mentioned base assembly; asecond pivot arm spaced from the first-mentioned pivot arm and pivotallyinterconnected with the second base assembly, said adapter memberinterconnecting the pivot arms.
 6. The articulated caster of claim 5wherein one of said pivot arms extends sideways through an openingprovided in the corresponding base assembly.
 7. The articulated casterof claim 1 wherein said pivot arm includes an upper end and an oppositelower end and wherein said opposite lower end is adapted to pivot aboutthe two axes.
 8. The articulated caster of claim 7 wherein said two axesare substantially perpendicular.
 9. The articulated caster of claim 8and wherein said two axes are disposed in said pivot block.
 10. Thearticulated caster of claim 7 wherein said base includes two sidemembers that are disposed on opposite sides of an opening provided insaid base said lower end of said pivot arm being disposed in saidopening and wherein said universal joint includes a bolt that passesthrough opposite sides of said two side members and wherein said pivotone of said pivot axes extends longitudinally through said bolt.
 11. Thearticulated caster of claim 1, said base assembly presenting a pair ofthe base surfaces, said pivot block presenting a pair of the firstsurfaces, each of which slidably engages a corresponding one of the basesurfaces.
 12. The articulated caster of claim 11, said base surfacesbeing in an opposed relationship and facing inwardly toward one another.13. The articulated caster of claim 12, said base including a pair ofside members between which the pivot block is located, said side memberseach defining a respective one of the base surfaces.
 14. The articulatedcaster of claim 1, said pivot arm presenting a pair of the arm surfaces,said pivot block presenting a pair of the second surfaces, each of whichslidably engages a corresponding one of the arm surfaces.
 15. Thearticulated caster of claim 14, said arm surfaces being in an opposedrelationship and facing inwardly toward one another.
 16. The articulatedcaster of claim 15, said pivot arm including a pair of side platesbetween which the pivot block is located, said side plates each defininga respective one of the arm surfaces.
 17. The articulated caster ofclaim 1, said arm surface and said base surface being perpendicularrelative to one another.
 18. The articulated caster of claim 17, saidfirst one of the axes intersecting the base surface, said second one ofthe axes intersecting the arm surface.